Diesel engines offer a benefit of increased fuel economy. However control of NOx emissions in such systems is complicated due to a high content of oxygen in the exhaust gases. Further, during a cold start of the diesel engine, a catalyst downstream of the diesel engine has a relatively low efficiency in reducing NOx since it does not reach a desired operational temperature level relatively quickly.
Accordingly, it is desirable to provide an improved exhaust gas aftertreatment system and a method for increasing a temperature of an SCR catalyst during engine startup to reduce NOx in exhaust gases from the diesel engine.